The term Jewish fundamentalism is used to refer to fundamentalist religious beliefs among Jews. The term "fundamentalism" was originally used in reference to certain Christian groups but today commonly refers to the anti-modernist movements of any religion based on literal interpretation of religious scriptures. Orthodox Judaism is characterized by a fervent belief in the divine origin of the Torah (i.e., that the five books of Moses were literally given by God).

Most streams of Judaism believe that the Tanach (Hebrew Bible, Old Testament) can not be understood literally or alone, but rather needs to be read in conjunction with additional material known as the oral law, contained in the Mishnah, Talmud, and subsequent legal codes. As one opinion in the Babylonian Talmud recorded in Brachot (laws of Blessings) states, every statement made by every student to their teacher was given to Moses on Sinai. This opinion may clearly be interpreted in many ways --- taken to extremes, the statement implies that each law within the tens of thousands of volumes of Jewish legal codes is regarded as sacred and infallible, even if it contradicts others, and there are undoubtably some who believe this.

However, the vast majority of Orthodox Jews don't believe this statement literally, but rather apply different gradations of holiness to each statement: Torah (divine) origin (e.g., the prohibition of eating/cooking/benefitting from mixtures of milk and domestically cultivated red meat), Rabbinic decree in order to better enforce Torah law (e.g., the prohibition of eating/cooking mixtures of milk and poultry or wild kosher game), Rabbinic decree for its own sake (e.g., three separate decrees of Rabbeinu Gershom in the year ~1000 CE banned reading another's mail, divorcing a woman without her consent, and polygamy.), custom (e.g., the European custom against eating beans and peas on Passover), etc.

Laws of Torah origin are regarded as most important, and are not easily superceded, although a risk to life supercedes Torah prohibitions. Laws of Rabbinic origin are still important, but are less rigid, so may be superceded to e.g., care for a non-serious illness. The general rule is "Doubt in a Torah law
is judged strictly; doubt in a Rabbinic law is judged leniently." A simplistic example is: if one doesn't remember saying a blessing before eating food, since this requirement is a Rabbinic law, one does not need to say the blessing.

Fundamentalism and the Israeli settlement movement

The Israeli settlement movement in the West Bank and Gaza is motivated by both secular and religious reasons. However, many of the most controversial settlement leaders are associated with Jewish fundamentalists who support the concept of "Greater Israel".

People in this group represent only a fringe of Israeli society, albeit a fringe that is well organized and has significant political clout through religious parties. One example of a supporter of Greater Israel is Rabbi Yisrael Ariel, formerly the rabbi of Yamit in the Sinai, and now of the Temple Institute of the Old City. In this view, Jews do not have to conquer the land of Israel, but if they do come to control it, they are forbidden to give it up. This was especially relevant with regard to Lebanon after the 1982 invasion.